Predicting the Formula of Ionic Compound

Predicting the Formula of Ionic Compound

  1. We can predict the charge of the ions formed from an element base on the group of the element.
  2. From the charge, we can then write the formula of the ionic compound formed.
  3. In short, we can predict the formula of an ionic compound if we know the group (in the periodic table) of the elements in the compound.
  4. The table below shows the formula of the ionic compounds formed by the elements from different group in a periodic table.
Elements
Formula of Ionic Compound
Examples
Atoms of Metal, MAtoms of Non-Metal, N
Group 1
Group 15
 M3N
Na3N
Group 1
Group 16
M2N
K2O
Group 1
Group 17
MN
LiCl
Group 2
Group 15
M3N2
Ca3N2
Group 2
Group 16
MN
MgO
Group 2
Group 17
MN2
BaBr2
Group 13
Group 15
MN
AlN
Group 13
Group 16
M2N3
Al2O3
Group 13
Group 17
MN3
AlI3

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